Access devices such as smart phones, net books, laptops with wireless access and similar user equipment (UE) are increasingly capable of using multiple wireless and wireline connectivity options (e.g., GSM/GPRS, UMTS, LTE, WiFi, USB/wired, Ethernet and so on). The services that can be supported in a single device will increasingly vary depending on the connections that are available. Ignorance of the wireless connection technology by the application, particularly within the extended suite anchored in the 3GPP core network (GSM/GPRS, EGPRS, UMTS, LTE, HSPA, eHRPD, 3GPP WLAN) makes it difficult to support the service adaptation necessary to maintain high subscriber satisfaction.
The specific access network and technology used by the access device is selected according to a fixed preference list stored in the device, or according to a preference list transmitted by the access provider. The preferences are typically meant to ensure that service is provided via the subscriber's access provider or a partner provider. The access technology is selected primarily according to signal strength (coverage) considerations and, after being selected, is used to support all services requested by the user.
The concept of “presence” entails network and/or application awareness of UE reachability when accessing a network. When user equipment is reachable, content and services may be delivered from application servers, and peer applications may interact with the UE. In mobile networks, presence is currently is a binary concept from the perspective of applications—the UE is reachable by the application (such as within the context of an established session), or it is not reachable. The specific access technology and the resulting capabilities are hidden from the application behind a common IP anchor point.
Unfortunately, there is presently no mechanism to provide explicit access technology feedback to applications to allow them to adapt their processing to the capabilities and/or limitations of the access network, particularly when the access technology is hidden by an anchor point in the 3GPP core network.
Application servers or their proxies in content delivery networks, generally adapt their processing according to the available bandwidth in an access network as sensed by protocols at IOS layers above the Network Layer in the OSI Reference model. For example, at the Transport layer, TCP uses trial and error to estimate the available connection bandwidth and avoid congestion. The amount of data that TCP sends on a connection during a Round Trip Time (RTT) depends on the size of a “Congestion Window” that limits the number of packets that may be in transit. TCP congestion avoidance adapts the Congestion Window when packet loss occurs, continually making adjustments as bandwidth varies on a time scale associated with round-trip packet delay.
Another example is RTCP (RTP Control Protocol) which operates out of band at the Application Layer and is used for controlling RTP streams (typically over UDP). RTCP gathers statistics such as packet loss, jitter, and delay for a media connection. An application server may use this information to control the media stream so it is more compatible with the transmission network. Mechanisms such as adaptive streaming have been developed to support this. Examples include Microsoft Silverlight, Apple iPhone HTTP live streaming, Move Networks adaptive streaming, and Adobe: Real Time Messaging Chunk Stream Protocol (RTMCSP) among others.
None of these methods for controlling application interaction with the access network provides for an application to be explicitly aware of the access technology and its capabilities. This results in several deficiencies, including.                Adapting by trial and error. Only when the bandwidth of the available access network is exceeded and errors (packet drops, excessive delay, etc.) occur can the application adapt its processing.        Adapting the nature of the service rather than the rate at which packets are transported or the encoding of the packets is difficult. This is especially true in wireless networks because end-end measurements can not discern systematic throughput restrictions due to technology choice limitations from transient rate fluctuations due to mobile geometry and RF fading.        Access provider control over how applications interact with their access networks becomes more difficult. For example, “low value” applications which require high bandwidth may compete on shared channels (for example the air-interface) with “high value” applications that require less bandwidth. This can lead to degradation in performance for the high value application. In practice, service providers prefer to explicitly limit the high bandwidth applications supported on air-interface technologies that have limited bandwidth. This is not possible with a multi-technology capable device unless a means is provided to explicitly indicate the access method to a controlling function, or to the application.        